1. Field of the Invention
The present invention relates to a photosensor to emit light to a target object and receive light reflected thereby as well as to an image forming device such as a copier, a printer or a facsimile machine incorporating such a photosensor.
2. Description of the Related Art
Some image forming device having a photosensor generates a toner patch as a referential pattern on the surface of an image carrier and detects the density of the toner patch for the purpose of realizing stable image density. To control image density, such an image forming device adjusts develop potential by changing charge bias, developing bias, and light intensity for forming an electric latent image or adjusts a target toner density of two-component developer in a develop unit on the basis of a detected result of the photosensor. This type of photosensor is generally a reflective photosensor having a light emitting element and a light receiving element.
Japanese Patent Application Publication No. 2008-261864 discloses a photosensor including light emitting and light receiving elements of a surface mount type on a printed circuit board. There are two types of light emitting element, a top view surface mount type to emit light to a printed circuit board orthogonally, and a side view surface mount type to emit light thereto in parallel. Likewise, a top view surface mount type light receiving element receives light orthogonally relative to the printed circuit board while a side view surface mount type light receiving element receives light in parallel to the printed circuit board. The same type of light emitting element and light receiving element are used together.
These light emitting element and light receiving element (hereinafter, referred to as simply element when appropriate) are each provided with L-shaped output terminal and input terminal composed of one portion extending to the printed circuit board and the other portion continuing from the end of the one portion and extending in parallel to the printed circuit board. To mount each of the elements on the surface of the printed circuit board, the other parallel portions of the terminals and the connecting portions of the printed circuit board are joined by soldering.
In fixing the element on the printed circuit board by soldering, only the pair of input and output terminals is placed thereon. That is, the element is supported by the two terminals only when mounted. This may cause a problem that the element is mounted in an unintended posture on the circuit board. For example, such a problem occurs when the extending portion and the parallel portion of the terminal make an angle other than a preset angle of 90 degrees due to a processing error. Further, there is a gap between the circuit board and the opposing surface of the element so that the element supported by the two terminals may be swayed about the terminals as fulcrum in the gap. Because of this, while melted solder between the connecting portions of the circuit board and the terminals is being hardened, the elements may be touched and swayed to partially contact the printed circuit board, and fixed thereto in an inclined posture.